In recent years, transistors that are compact and allow a large current to flow have become necessary as the integration of semiconductor devices increases. A fin transistor (a finFET) in which the upper surface of a semiconductor substrate is patterned into a fin configuration and a gate electrode is provided to straddle the fin has been proposed as such a transistor. In such fin transistors, the amount of current per chip surface area is large because the proportion of the channel width to the chip surface area is large. However, an even larger current is necessary for such fin transistors.